652 Bulletin American Museum of Natural History. [Vol. XXIV, 



This species is named in honor of Dr. F. W. True, Curator of the Depart- 

 ment of Biology, U. S. National Museum, who was the first to make known 

 the occurrence of any member of the Octodontidse in Central America. 1 



19. Heteromys vulcani sp. nov. 



Type, No. 28315, 9 ad., Volcan de Chinandega, altitude abDut 4000 feet, May 4, 

 1907; W. B. Richardson. 



Soles hairy, 5-tuberculate ; no lateral line. Above blackish, varied with gray, 

 owing to the whitish basal portion of the spines showing at the surface, especially' 

 on the sides, black prevailing over the median area; ventral surface and inside of 

 limbs white or yellowish white; fore limbs wholly white; hind limbs externally like 

 the dorsal surface; fore and hind feet white; ears small, rounded, scantily haired, 

 dark brown or blackish, very faintly edged with w r hite; tail bicolor, blackish above, 

 whitish below, very scantily haired, the annulations unconcealed, and slightly 

 tufted. In the adults the spines are heavy, nearly without intervening hairs; in 

 younger specimens the spines are weaker and mixed with dark hairs, annulated with 

 pale rufous, giving a slight ruddy tinge to the dorsal surface. 



Total length (type), 220 mm. ; tail, 110; hind foot, 25 (collector's measurements). 

 Four adult specimens, total length, 205 (190-220) ; tail, 100 (90-110). Skull (type), 

 total length, 31 ; condylo-basal length, 27 ; zygomatic breadth, ; interorbital breadth, 

 7; mastoid breadth, 14; length of nasals, 11; breadth of rostrum at middle, 5; 

 upper molar series, 4. Four other adult skulls give the same total length, and 

 practically the same mastoid breadth. 



This species is represented by 12 specimens, mostly adult, but several 

 are in poor condition. Nearly all are from the type locality. 



Heteromys vulcani is easily recognized by the combined characters of 

 small size, hairy soles, fore limbs wholly white, and absence of a lateral line. 

 The type is the only specimen in the series in which the tail exceeds 100 mm. 

 The nasals are emarginate or V-shaped posteriorly, and terminate slightly 

 in advance of the posterior border of the premaxillse. 



20. Heteromys fuscatus sp. nov. 



Type, No. 28451, tf ad., Tuma, Nicaragua, Dec. 1, 1907; W. B. Richardson. 



General color above blackish, darker on the head, slightly varied with buffy 

 gray; back slightly suffused with fulvous; sides pale fulvous strongly lined with 

 black; top and sides of nose nearly black; thighs and outer surface of hind limbs and 



1 ' On the Occurrence of Echinomys semispinosus Tomes, in Nicaragua.' Proc. U. S. Nat. 

 Mus., XI, 1888, pp. 467, 468. 



This record is based primarily on three specimens collected in the vicinity of Greytown, 

 which proved to be not E. semispinosus Tomes, but referable to a new species later described 

 by Thomas, from Nicaragua specimens, as E. centralis. In the same connection he also made 

 mention of three specimens from Pacuare, Costa Rica, likewise referred by True to E. semi- 

 spinosus. Through the kindness of Dr. M. W. Lyon, curator of mammals at the U. S. National 

 Museum, these six specimens have been sent to me for examination, and all prove to be referable 

 to Proechimys centralis. 



